1. Field of the Invention
The present invention relates in general to air bag devices and method of producing same. More particularly, the invention relates to air bag devices for use in a wheeled motor vehicle, which generally comprise a housing fixed to a vehicle body, a gas generator unit installed in the housing and an air bag folded up in the housing with a gas inlet opening thereof connected with a gas outlet opening of the gas generator.
2. Description of the Prior Art
Hitherto, various types of air bag devices have been proposed and put into practical use particularly in the field of wheeled motor vehicles. That is, upon a vehicle collision, an air bag is instantly inflated to protect a passenger seated in front of the air bag device. Some of the conventional air bag devices are described in Japanese Patent 2523406, Japanese Patent First Provisional Publication 8-119059 and Japanese Utility Model First Provisional Application 61-185642.
In order to clarify the task of the present invention, one conventional air bag device 100 will be described in brief with reference to FIGS. 5 and 6 of the accompanying drawings.
The conventional air bag device 100 shown in the drawings comprises a housing 3 (see FIG. 6), a cylindrical gas generator unit 5 installed in the housing 3 and secured to the same by means of bolts 8a and nuts 8b, and an air bag 7 connected at its inlet opening 7a to an outlet of the gas generator unit 5. As shown in FIG. 5, the gas generator unit 5 comprises a cylindrical case 11 and a cylindrical gas generator proper 5a concentrically installed in the cylindrical case 11. The inlet opening 7a of the air bag 7 is connected to an outlet opening of the gas generator proper 5a through openings 11a formed in the cylindrical case 11.
As is seen from FIG. 5, the air bag 7 has at the inlet opening 7a two opposed flaps 9a and 9b each having bolt openings 9c and 9d. As is understood from FIG. 6, upon assembly, the two flaps 9a and 9b are put around the cylindrical case 11 with their leading end portions overlapped having the bolts 8a passed through the bolt openings 9c and 9d which are registered.
However, due to its inherent construction, the above-mentioned conventional air bag device 100 has the following drawback.
As is understood from FIG. 6, upon inflation of the air bag 7, leakage "L" of gas tends to occur at lateral sides of the inlet opening 7a of the air bag 7. In fact, it is difficult to seal such lateral sides because they are substantially exposed to the outside.